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BaseRepresentation
bin100100111100111
3221221201
410213213
51101134
6223331
7106105
oct44747
927851
1018919
111323a
12ab47
1387c4
146c75
155914
hex49e7

18919 has 2 divisors, whose sum is σ = 18920. Its totient is φ = 18918.

The previous prime is 18917. The next prime is 18947. The reversal of 18919 is 91981.

It is an a-pointer prime, because the next prime (18947) can be obtained adding 18919 to its sum of digits (28).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18919 - 21 = 18917 is a prime.

It is a super-2 number, since 2×189192 = 715857122, which contains 22 as substring.

Together with 18917, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9459 + 9460.

It is an arithmetic number, because the mean of its divisors is an integer number (9460).

218919 is an apocalyptic number.

18919 is a deficient number, since it is larger than the sum of its proper divisors (1).

18919 is an equidigital number, since it uses as much as digits as its factorization.

18919 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 648, while the sum is 28.

The square root of 18919 is about 137.5463558223. The cubic root of 18919 is about 26.6460430819.

The spelling of 18919 in words is "eighteen thousand, nine hundred nineteen".